Cemented hard carbide material



' used as'a tool for cutting steels than the compo-.

.' Patented Sept. 11,1934

UNITE-D STATESJPATBNT omen .v

1,973,428 CEMEN'I'ED man ommn'm'raamn Gregory J. Comstock, Edgcwoorl, Pa. assignor'to Firth-Sterling Steel CompanmMcKeeeport, 2a.,

a corporation of Pennsylvania Y No Drawing.

Application November 8, 1932, Serial No. 641,762 r 3 Claims. (ems-1) materials made by a cementing and more particularly to mented carbide or sintering process,

such materials containing tungsten carbide, tan:-

5 talum carbide, titanium carbide and an auxiliary metal, or alloysuch as cobalt, iron or nickel.

Hard cemented carbide materials containing tungsten carbide and iron, cobalt. or nickel are now known and have been described in Schroeter Patent No. 1,549,615. In my application, Serial No. November 4, 1931,

cemented carbidematerial containing tungsten carbide, tantalum carbide and cobalt, nickel or iron. This composition exhibits less wear when 512,917, filed sition of the Schroeter Patent. It has a lower heat conductivity and has less tendency to form the detrimental chip cavity behind the cutting edge of the tool thanv the Schroeter material. It alsohas been proposed to-use a mixture of tungsten carbide, titanium carbide, and an auxiliary metal. Although this composition, composition described in my application Serial bio. 572,977, exhibits reduced wear and has alower heat conductivity then the Schroeter comtungsten carbide and cobalt,

the composition containing tungsten carbide, ti-.

tanium carbide and cobalt is more brittle and the commercial product has a tendency to exhibit free graphite which reduces the hardness and strength of the material.

I have found that a superior compositioncan be made by cementing a mixture of tungsten carbide, tantalum carbide, titanium carbide and an auxiliary metal such as cobalt, iron or nickel. This composition has a lower heat conductivity and afiords a further resistance to wear and to the formation of chip cavity when used as a tool material, as compared with any of the other compositions referred to. These properties are obtained at little or no increase in the brittleness oi the composition and in some cases produces a toughening effect. In addition, the composition produces/a bright, smooth out on the material being mac i I N. when it is employed 'inthe' high speedmac t of steel.

in carrying out the invention, tungsten carbide, tantalum carbide, titanium carbide and 5 either cobalt, iron or nickel or I a mixture of these auxiliary metals, but preferably cobalt, are

mixed together by milling them in a ball mill accordance with the usual process in prep finely divided materials for sintering. This mix- 55 ture may be sintercd or cemented by either the there isdescribed a hard.

likethetween .5 and cold-press, method or the hotpress' method. In the cold-press method thefmixtureis compacted into 'a billet under relatively high'pressure, for

example 10,000#/sq.- in. and is then preferably given'a preliminary sinter at about 1600 -F. f

, It is cooled and :reshaped'and then given a final I I sinter at a temperature of between 2600 and 3200 E,

The material may be made according to the hot-press method in which the heat and pressure 65 are applied simultaneously. We preter in the hot-press, method to use. a temperature of about 3200 F. and a pressure of about 140o#/sq. in'. and. to carry out the sinteringfor, about five minutes at thisftemperature. Other temperal0 tures andpressures may, however, be used satisfactorily according to the particular composition.

The percentages of tungsten carbide, tantalum carbide, titanium carbide and auxiliary metal may be varied within wide limits and still pro- 75 duce satisfactory results. The tungsten carbide may vary between and 80% by weight of the entire mixture, but it is preferably between and The tantalum carbide may vary between 5 and 45%, but preferably is between 10 and 35%. The titanium carbide may vary beand preferably between 3 and 20%. The auxiliary metal, preferably cobalt, may vary between 1 and 30% and is usually maintained between 5 and 15%.

A composition which I have found to exhibit very superior properties contains: tungsten carbide 57.96%, tantalum carbide 24.84%, titanium carbide 10%, cobalt, iron or nickel 7.20%.

The tungsten carbide generally is used in greater proportion than either the tantalum carbide or the titanium carbide, and the tantalum carbide is generally used in higher proportions than the titanium carbide. Furthermore, the titanium carbide usually increases with the amount of auxiliary metal.

It is to be understood that one or more auxiliary metals may be used in place of a single auxiliary metal. The term auxiliary metal is used in a broad sense to cover not only the metal per se, but also alloys formed between the auxiliary metals themselves when more than one auxiliary metal is used or between an auxiliary metal and the hard metal carbide or carbides. m

I have described the present preferred embodiment of my invention. It is to be understood; however, that the invention may be otherwise embodied wi I claim: g

1. A hardicemented carbide material containing about 35 to 80% tungsten carbide, about 5 to 45% tantalum carbide,-and about .5 to 30% 5 titanium carbide, the remainder consisting essentially of an auxiliary metal of the group consisting of cobalt, iron and nickel in the range of about 1 to 30%, the proportion of tungsten carbide being greater than either the tantalum g carbide or titanium carbide.

2. A hard cemented carbide material containing about 50 to 70% tungsten carbide, about 10 GREGORY J. COMSTOCK. 

